Palate development will be studied in mice, rats and rabbits and cleft lip will be studied in mice. The potential role of embryonic muscular movements in normal palate development and the possible diminution of these movements under conditions producing cleft palate will be investigated. Existing techniques for the observation and manipulation of living embryos will be utilized and efforts will be made to increase the range and validity of these techniques. The morphology of normal and abnormal palate development will be studied by histometric, electron microscopic, and radioautographic techniques. The electron microscopic studies will be directed primarily to skeletal muscle that may be involved in palatine shelf transposition.